Study of agarose gels by electron microscopy of freeze-fractured surfaces

✍ Scribed by Seichi Waki; J. D. Harvey; A. R. Bellamy

• Publisher: Wiley (John Wiley & Sons)
• Year: 1982
• Tongue: English
• Weight: 1012 KB
• Volume: 21
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.360210917

✦ Synopsis

Abstract

The distribution of fibers in agarose gels has been studied by electron‐microscopic examination of replicas formed from freeze‐fracture surfaces. For gels set in water, the results obtained support the model proposed for the gel structure by Arnott et al. (1974) of a random array of long, straight, connected fibers, with each fiber having a diameter equivalent to that of an aggregate of approximately 10–30 agarose helixes, depending on the initial agarose concentration. The density of these fibers, their water content, and the total length of fibers per unit volume have been derived from the measured distribution of intersections per unit area of freeze‐fracture surfaces. For gels set in the presence of salt, the distribution of fibers becomes distinctly non‐Poissonian, leading to larger interfiber spaces and a gel of greater effective pore size. The larger pore size of gels set in the presence of salt also has been revealed by electrophoretic measurements in which the relative migration rates of plasmid DNA molecules of varying conformations have been determined.